A three-dimensional (3D) image may represent reality of a real physical world, and have advantages of presence feeling, reality, naturalness, vividness, and the like.
Techniques for representing a 3D image may include a stereoscopic method and holographic method. The stereoscopic method uses a left side and a right side, that is, two two-dimensional (2D) images, and the holographic method uses diffusion of an object.
The holographic method aims to represent a 3D image more graphically using light diffused from an object. However, the holographic method in the present stage may not embody a 3D image in real time using current transmission systems due to a great amount of 3D information and a limit of related elements.
The stereoscopic method uses a principle of a human visual system (HVS). Specifically, humans perceive different images of an object from each eye due to a location difference of the left and right eye, and perceive the object in three dimensions, which is used in the stereoscopic method. That is, parallax associated with the fact that both eyes of human are apart from each other by approximately 65 mm is a critical point of cubic effect of human.
The stereoscopic method enables the left and right eye to each see different 2D images using a plurality of display devices, or enables different 2D images to be repeatedly displayed at regular intervals using a single display device. Accordingly, the stereoscopic method enables a user to synthesize two light sources reflected from an object, and thereby may create perspective and reality.
Thus, the stereoscopic method requires two 2D images different from each other.
In general, an Initial Object Descriptor (IOD), Scene Descriptor (SD), Object Descriptor (OD), and media data are required to create an image based on a Moving Picture Experts Group-4 (MPEG-4). An IOD is information to be first transmitted to compose an MPEG-4 scene, and defines a media profile and level. Also, an IOD includes an Elementary Stream (ES) descriptor about an SD stream and OD stream. An OD is a set of ES descriptors describing information about media data included in a scene, and provides information about a connection between an SD and ES of media data.
An SD is for embodying a real-time two-way video data service or interactive data broadcasting, and enables a two-way service interoperated with a program. Accordingly, SD is capable of interactive service according to users' needs.
In a conventional art, a technology to provide stereoscopic contents is disclosed in Korean Patent Unexamined Publication No. 10-2004-0090523 entitled ‘System and Method of Internet Broadcasting for MPEG-4 based Stereoscopic Video’. In the patent, an Internet (Internet Protocol-based network) broadcasting system which provides an MPEG-4 based stereoscopic 3D movie service, and Video On Demand (VOD) and live service via Internet may be provided. The technology may enable a user to enjoy contents of a 2D or 3D image via the Internet.
The technology in a conventional art provides a receiving/transmitting system and storage format to provide a stereoscopic video service based on an MPEG-4 system. However, the technology in a conventional art may not perform a 2D/3D display mode conversion using an SD and provide a stereoscopic text, video, and still image. Accordingly, a technology to overcome such disadvantages is required.